The RS485 temperature sensor implementation into the Modbus system
Have you ever wondered how to pair the RS485 temperature sensor to the existing Modbus system? Modbus can use several protocols including RS485, RS232, RTU, TCP/IP,… The RS485 temperature sensor is therefore made for the most common and most widely used Modbus protocol by far. The sensor can usually be installed in connected to existing building managing systems without any problems because the Modbus RS485 protocol is very widely used in industrial implementations.
1. RS485 temperature sensor implementation into Modbus system
The RS485 temperature sensor can be implemented into almost any Modbus system. RS485 protocol is very similar to RS232 and both are used to implement serial data communication. The difference between them is that they use different electric signals to enable data transmission.
Why is it RS485 protocol so widely used? Because of its ability to serve several devices attached to the same bus. That kind of system eliminates the need to have several interfaces available while querying several or multiple devices. RS485 protocol can connect directly to USB, Ethernet ports, or GSM. This approach is less expensive and also removes the requirement of the use of any additional components.
The next huge advantage of the RS485 protocol is also that it provides half-duplex transmission on a balanced line covering distances to 1200m.
The RS485 network is build based on a master/slave framework. The slave acts as a receiver to the master which performs the transmission, making requests to the slave devices and listens for the requests in an appropriate time-frame. Otherwise, the master will terminate the communication.
And that’s the basic principle of communication even for Andivi’s RS485 temperature sensor which means, that it can be implemented into almost any Modbus system. Find out more about the benefits of using the Modbus sensors here.
2. The principle of Modbus messages
In a Modbus network, system, or BMS, whatever we call it, communication always begins when the master sends a query to a slave device that spends its time monitoring the network for any kind of queries that are addressed to it. When such a query is received, the slave will either act or reply with a response to its master device. We have to understand also that the queries are only initiated by the master device.
The master device has an opportunity to address messages to a specific slave device only or communicate with all the slave devices simultaneously. Such communication is done using a special broadcast address.
Write and read operations are sent through Modbus messages using coils. Every coil consists of 16-bit words and binary registers which means that the slave device can only respond to a received message and it can never initiate a communication with the master device.
Every slave device which is attached to the RS485 bus connection is assigned with a unique Mobus slave ID. The ID is used by the master device to determine which slave device it wants to communicate with. A slave device, therefore, accepts a query or information from a master which was supplied directly to it.
3. The master and the slave – Andivi Modbus products
Andivi works with Modbus protocol for more than 20 years. We have designed numerous industrial projects on it and we are more than satisfied with its usability. We believe it is still the most commonly used and well-known industrial standard to date. So which product would be a master and which would be a slave?
The Modbus master is our controller U-DDC which can address all of the Modbus slave devices without any interruptions at all. It is also possible to expand it with additional input-output units called U-MIO. With such a expansions one single U-DDC controller can control almost entire building alone (depending on the inputs and outputs as well).
More information about our U-DDC controller can be found here.
The RS485 temperature sensor is a Modbus slave device, which listens to queries that the controller U-DDC sends to it. The measuring temperature can be easily transformed into the project needs whether it’s to change the heating, cooling, air conditioning systems, etc. Controlling the temperature with Modbus sensors is reliable, precise, and fast.
More information about our RS485 temperature sensor or Modbus temperature sensor can be found here.
Please do not hesitate to contact us.